This is a basic escape from the guard which may not work very well against opponents with very strong legs.
You are inside your opponents guard.
Grab hold of your opponents belt with your fingers over the top.
This technique may work better if your take one knee out to the side whilst placing your other knee at the base of your opponents spine. If using this approach be careful that your opponent doesn't reverse the technique and sweep you.
To break your opponents guard, simply push down and forward until they uncross their feet. You have to be careful with this technique since you are straightening your arms, making arm-bars quite easy for your opponent.